1. Field of the Invention
The present invention relates to piezoelectric materials and in particular to active fiber composites comprising piezoelectric materials.
2. Description of Related Art
Piezoelectric materials can be arranged as fibers and combined with electrodes to yield active fiber composites. Hagood, I V et al. (U.S. Pat. No. 5,869,189) teaches composites for actuating or sensing deformation. The piezoelectric fibers are arranged in a parallel array with adjacent fibers separated by a soft polymer. Hagood further teaches flexible conductive material extending along the axial extensions of the fibers for imposing or detecting an electrical field.
Wilkie (U.S. Pat. No. 6,629,341) is directed to a method of fabricating a piezoelectric composite apparatus. Wilkie teaches a piezoelectric macro-fiber composite comprising a PZT-5 piezoelectric ceramic material formed into a wafer.
Chiang et al. (U.S. patent application publication number 2006/0102455) teaches an electrochemical actuator. The electrochemical actuator includes a support system including both top and bottom fibers. The top and bottom fibers are inert and are used to support the electrochemical actuators.
The related art has several shortcomings. The related art includes actuator designs with printed electrodes that have a small contact region between the actuating fibers and the electrodes. Furthermore, printed electrode designs can lead to sharp points in the electrodes that may cause localized regions of high stress and/or strain. Additionally, it can be difficult to achieve proper electrode alignment using current designs, which can reduce overall symmetry. All of these features can lead to a reduction in actuation authority and actuation efficiency. There is a need in the art for a design that overcomes some of these shortcomings.